1. Field of the Invention
The invention relates to graft copolymers of ethylenically unsaturated monomers and unsaturated polyols containing alkenyl aryl constituents. The invention further relates to the use of these graft copolymers in polyurethane formulations.
2. Prior Art
A great deal of art has arisen focusing on methods for increasing the overall molecular weight of polyols without seriously affecting chain length and attendant fluidity, by incorporating polymeric materials onto the polyol by grafting. Such graft copolymer polyol dispersions have proven to be advantageous when used in polyurethane formulations to achieve desirable polyurethane product properties such as enhanced load bearing and resiliency in foams.
It is known in the art to prepare graft copolymer dispersions from vinyl monomers and polyols and to use these copolymers in the formulation of urethane polymers. For example, U.S. Pat. No. 3,383,351 to Stamberger teaches that ethylenically unsaturated monomers may be polymerized in a polyol medium. As evidenced by Patton et al in U.S. Pat. No. 3,966,521, graft copolymers could also be formed by reacting vinyl monomers in polyols containing some degree of unsaturation. Both of these patents, however, fail to show graft copolymers which are prepared from vinyl monomers and alkenyl aryl polyols.
Graft copolymers also are described in U.S. Pat. No. 3,190,925 to Stowe which are prepared by copolymerizing an ethylenically unsaturated monomer with an alkenyl benzyl polyglycol such as: ##STR1## However, these graft copolymers are not prepared from alkenyl aryl polyols, and, hence, do not contain the multiple hydroxyl groups as are required for use in polyurethane formulations.